The Roland System-500 530 Dual VCA is a modern Eurorack adaption (via Josh Holley at Malekko) of the old System-100 130 Dual VCA module. In the first of two videos, I demonstrate taking advantage of both its audio input and control voltage mixers, explore its internal gain structure, and show a pseudo-stereo application using its two halves:
In the second of the two videos, I focus on its Exponential vs. Linear response switch, including using it with an envelope generator (an Intellijel Quadra) that also has both linear and exponential shapes:
There is also an accompanying article on LearningModular.com that goes into more detail about linear versus exponential envelopes and VCAs, and includes both the movie above and a second movie that demonstrates the continuously variable envelope shapes of the WMD MultiMode Envelope.